1. Field of the Invention
The present invention relates generally to the field of image processing. More specifically, the present invention relates to a method and apparatus for using a reference lighting map to compensate for uneven lighting in an image of a surface.
2. Related Art
Digital scanner and color printer technology have advanced to the point where it is possible to make high quality copies of color photographs and color documents. Unfortunately, some documents cannot be scanned using a scanner. For example, a visitor to a museum cannot scan a historical document or a painting on display.
One technique to capture images of documents that cannot be scanned is to take a high-quality photograph and to digitally scan the photograph. Another technique is to use a high-resolution digital camera to capture an image of the document. Unfortunately, unlike a digital scanner, a digital camera does not provide an even light source to the document to be scanned. Instead, the digital camera relies on the ambient lighting and/or a flash-lamp to illuminate the document while capturing an image of it. Therefore, images captured using these techniques typically exhibit uneven lighting, even if care is taken when positioning the camera to take a picture of the document.
Hence, what is needed is a method and an apparatus for correcting for uneven lighting in an image of a surface.